If you went to a zoo in the middle of the 1900s, chances are you would see many different species of animals than you would at a modern zoo. Back then, zoos were like living postage stamp collections, having one or two of as many species as possible. At the time, most species of animals at the zoo were still plentiful in nature, and getting new animals to replace those that grew old was not a problem, so no one concentrated on breeding programs.

Zoos of today have changed a great deal since then. Whereas once many zoos considered themselves to be places of amusement, today nearly all of the reputable zoos in the United States consider themselves to be conservation organizations. The Wildlife Conservation Society, which operates the Queens Zoo (as well as the Central Park and Prospect Park Zoos) on behalf of the City of New York and owns the Bronx Zoo and the New York Aquarium, has a simply stated mission: To save wildlife and wild places.

We do this by showing people amazing animals and building an appreciation for wildlife amongst our visitors. Because we are interested in saving wildlife, zoos do their best to keep healthy, plentiful populations of animals to show the public that they no longer have to be taken out of the wild, they are born and raised zoos. We place much more emphasis on breeding animals in the zoos than was done in zoos of the past.

By breeding animals rather than capturing them from the wild, zoos have had to change much of their exhibit strategy. If we still kept one or two individuals of every species, we would certainly not be able to breed very many animals for very long. (For example, if a pair of bison produced a calf, that calf would be without a mate when it reached maturity.) Zoos now focus on exhibiting larger groups of self-sustaining animals.

To further increase the population available for breeding, the zoos belonging to the American Association of Zoos and Aquariums (AZA) have created programs called Species Survival Plans (SSP) for a number of endangered species. The SSP works by making sure all zoos that own individual animals of any SSP species treat those animals as a single population; agreeing to abide by a committee decision about the best way to breed that species so new animals need not be removed from the wild.

For example, years ago, the Queens Zoo had a pair of Andean bears that were twin brothers. The SSP committee for the Andean bears recommended that we send one of the twins to the St. Louis Zoo to be paired with a female bear.

At the same time a small zoo in Tennessee was to send Queens Zoo a female that had no offspring yet but was not kept with a male. To make room for the bear from Queens Zoo, the St. Louis Zoo had to send their older male bear out to another zoo. All the involved zoos agreed to these recommendations, and today there are three zoos with Andean bears hoping for cubs.

Without the SSP none of these facilities would have had breeding pairs unless they bought new bears. SSP programs exist for over 100 different species in zoos and aquaria. In this way, zoos hope to bring the wonder and appreciation of wildlife to the public for generations to come while leaving the wild populations to thrive in their native habitats.

Scott Silver is the Director of the Wildlife Conservation Society’s Queens Zoo.